In attempting to develop a chemical which would make a person super-intelligent, Dr. Montrose fails and the subjects of his experiments metamorphose into hideous monsters who band together and prey on humans. With the police stymied, a young detective attempts to track down the leader of the group of killers, known only to have a small crimson stain in one eye.
Maurice Costello
as Harold Stanley
Ethel Grandin
as Florence Montrose
Thomas J. McGrane
as Dr. Burton Montrose
Olga Olonova
as Vanya Tosca
William Cavanaugh
as Doctor's Assistant
John A. Milton
as Layton Parrish (as John Milton)
N.J. Thompson
as Jim Tanner
Eugene Strong
as Robert Clayton
Lorna Volare
as Little girl
